This invention relates to improvements on a medical instrument, for example, forceps attached to an endoscope and inserted therewith into the body cavity of human beings.
Various medical treatments have been carried out, as is well known, by conducting a medical instrument, for example, forceps into the body cavity of human beings through a channel specifically formed in an endoscope during observation of an effected portion appearing in said body cavity. A medical instrument attached to the endoscope generally comprises an elongate flexible tube; a movable head supported at the tip of said flexible tube; forceps having a pair of cutting cups; a base member disposed at the base end of the flexible tube, designed to be gripped by operator's fingers and provided with a ring-shaped finger hook; an actuating wire inserted into the flexible tube so as to slide lengthwise thereof, having its forward end operatively connected to the movable head and actuating the movable head by sliding relative to the flexible tube; and a slider fitted with the base end of the actuating wire and mounted on the base member so as to slide lengthwise thereof so as to cause the sliding of said wire. The medical instrument is conducted into the human body cavity through the endoscope channel with the movable head kept foremost.
Hitherto, it has been necessary for an operator to manipulate the medical instrument by one of his hands while operating an endoscope by the other hand for observation. In the case of forceps, the operator had to move the slider relative to the base member by inserting the thumb of said one hand into the ring-shaped finger hook of the base member and gripping the slider by the forefinger and middle finger of said one hand, thereby actuating a pair of cups disposed at the tip of the flexible tube.
The prior art forceps were provided with a locking mechanism which included a toothed portion formed lengthwise of the base member, a pawl supported on the slider for engagement with said toothed portion and a spring for urging the pawl toward said toothed portion.
With the conventional locking mechanism, the operator had to keep the pawl disengaged from the toothed portion against the force of a spring while moving the slider free from the base member. Such one hand-operation of the medical instrument was accompanied with considerable difficulties and failed to render said operation very accurate.